5-1

FAST AND LS TTL DATA

ONE-OF-TEN DECODER

The LSTTL / MSI SN54 / 74LS42 is a Multipurpose Decoder designed to ac-

cept four BCD inputs and provide ten mutually exclusive outputs. The LS42
is fabricated with the Schottky barrier diode process for high speed and is
completely compatible with all Motorola TTL families.

•

Multifunction Capability

•

Mutually Exclusive Outputs

•

Demultiplexing Capability

•

Input Clamp Diodes Limit High Speed Termination Effects

14

13

12

11

10

9

1

2

3

4

5

6

VCC

7

16

15

8

A0

A1

A2

A3

9

8

7

0

1

2

3

4

5

6

GND

NOTE:
The Flatpak version has the
same pinouts (Connection
Diagram) as the Dual In-Line
Package.

CONNECTION DIAGRAM DIP (TOP VIEW)

PIN NAMES

LOADING (Note a)

HIGH

LOW

A0 – A3
0 to 9

Address Inputs
Outputs, Active LOW (Note b)

0.5 U.L.

10 U.L.

0.25 U.L.

5(2.5) U.L.

NOTES:
a) 1 TTL Unit Load (U.L.) = 40

µ

A HIGH/1.6 mA LOW.

b) The Output LOW drive factor is 2.5 U.L. for Military (54) and 5 U.L. for Commercial (74)

Temperature Ranges.

3

LOGIC DIAGRAM

14

4

5

10

11

12

13

15

1

2

6

7

9

1

2

3

4

5

6

0

A0

A1

A2

A3

9

8

7

VCC = PIN 16
GND = PIN 8

= PIN NUMBERS

SN54/74LS42

ONE-OF-TEN DECODER

LOW POWER SCHOTTKY

J SUFFIX

CERAMIC

CASE 620-09

N SUFFIX

PLASTIC

CASE 648-08

16

1

16

1

ORDERING INFORMATION

SN54LSXXJ

Ceramic

SN74LSXXN

Plastic

SN74LSXXD

SOIC

16

1

D SUFFIX

SOIC

CASE 751B-03

LOGIC SYMBOL

VCC = PIN 16
GND = PIN 8

15

14

13

12

0 1 2 3 4 5 6 7 8 9

1 2 3 4 5 6 7 9 10 11

A0 A1

A2

A3

5-2

FAST AND LS TTL DATA

SN54/74LS42

FUNCTIONAL DESCRIPTION

The LS42 decoder accepts four active HIGH BCD inputs

and provides ten mutually exclusive active LOW outputs, as
shown by logic symbol or diagram. The active LOW outputs
facilitate addressing other MSI units with LOW input enables.

The logic design of the LS42 ensures that all outputs

are HIGH when binary codes greater than nine are applied

to the inputs.

The most significant input A3 produces a useful inhibit func-

tion when the LS42 is used as a one-of-eight decoder. The A3
input can also be used as the Data input in an 8-output
demultiplexer application.

TRUTH TABLE

A0 A1 A2 A3 0

1

2

3

4

5

6

7

8

9

L

H

L

H

L

H

L

H

L

H

L

H

L

H

L

H

L
L

H
H

L
L

H
H

L
L

H
H

L
L

H
H

L
L
L
L

H
H
H
H

L
L
L
L

H
H
H
H

L
L
L
L
L
L
L
L

H
H
H
H
H
H
H
H

L

H
H
H
H
H
H
H
H
H
H
H
H
H
H
H

H

L

H
H
H
H
H
H
H
H
H
H
H
H
H
H

H
H

L

H
H
H
H
H
H
H
H
H
H
H
H
H

H
H
H

L

H
H
H
H
H
H
H
H
H
H
H
H

H
H
H
H

L

H
H
H
H
H
H
H
H
H
H
H

H
H
H
H
H

L

H
H
H
H
H
H
H
H
H
H

H
H
H
H
H
H

L

H
H
H
H
H
H
H
H
H

H
H
H
H
H
H
H

L

H
H
H
H
H
H
H
H

H
H
H
H
H
H
H
H

L

H
H
H
H
H
H
H

H
H
H
H
H
H
H
H
H

L

H
H
H
H
H
H

H = HIGH Voltage Level
L = LOW Voltage Level

GUARANTEED OPERATING RANGES

Symbol

Parameter

Min

Typ

Max

Unit

VCC

Supply Voltage

54
74

4.5

4.75

5.0
5.0

5.5

5.25

V

TA

Operating Ambient Temperature Range

54
74

– 55

0

25
25

125

70

°

C

IOH

Output Current — High

54, 74

– 0.4

mA

IOL

Output Current — Low

54
74

4.0
8.0

mA

5-3

FAST AND LS TTL DATA

SN54/74LS42

DC CHARACTERISTICS OVER OPERATING TEMPERATURE RANGE

(unless otherwise specified)

S

b l

P

Limits

U i

T

C

di i

Symbol

Parameter

Min

Typ

Max

Unit

Test Conditions

VIH

Input HIGH Voltage

2.0

V

Guaranteed Input HIGH Voltage for
All Inputs

VIL

Input LOW Voltage

54

0.7

V

Guaranteed Input LOW Voltage for

VIL

Input LOW Voltage

74

0.8

V

p

g

All Inputs

VIK

Input Clamp Diode Voltage

– 0.65

– 1.5

V

VCC = MIN, IIN = – 18 mA

VOH

Output HIGH Voltage

54

2.5

3.5

V

VCC = MIN, IOH = MAX, VIN = VIH

VOH

Output HIGH Voltage

74

2.7

3.5

V

CC

, OH

,

IN

IH

or VIL per Truth Table

VOL

Output LOW Voltage

54, 74

0.25

0.4

V

IOL = 4.0 mA

VCC = VCC MIN,
VIN = VIL or VIH

VOL

Output LOW Voltage

74

0.35

0.5

V

IOL = 8.0 mA

VIN = VIL or VIH
per Truth Table

IIH

Input HIGH Current

20

µ

A

VCC = MAX, VIN = 2.7 V

IIH

Input HIGH Current

0.1

mA

VCC = MAX, VIN = 7.0 V

IIL

Input LOW Current

– 0.4

mA

VCC = MAX, VIN = 0.4 V

IOS

Short Circuit Current (Note 1)

– 20

–100

mA

VCC = MAX

ICC

Power Supply Current

13

mA

VCC = MAX

Note 1: Not more than one output should be shorted at a time, nor for more than 1 second.

AC CHARACTERISTICS

(TA = 25

°

C)

S

b l

P

Limits

U i

T

C

di i

Symbol

Parameter

Min

Typ

Max

Unit

Test Conditions

tPLH
tPHL

Propagation Delay
(2 Levels)

15
15

25
25

ns

Figure 2

VCC = 5.0 V

tPLH
tPHL

Propagation Delay
(3 Levels)

20
20

30
30

ns

Figure 1

CC

CL = 15 pF

AC WAVEFORMS

VIN

VOUT

1.3 V

1.3 V

1.3 V

1.3 V

tPHL

tPLH

Figure 1

Figure 2

1.3 V

1.3 V

1.3 V

1.3 V

tPLH

tPHL

VIN

VOUT